Skip to main content

Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"

See other formats


1.66

IRON

With pig iron containing 3-4% of carbon, i gram is taken ; with steel
containing more than 0-3%, 3 grains, and with soft iron containing less
than 0-3%, 5 grams.

When the liquid in the- lla.sk is quite cold I he absorption bulbs are fitted,
a little sulphuric acid is placed in the funnel /, the condenser is raised and
the weighed metal introduced into the flask, the condenser being then
rapidly replaced and a little sulphuric acid poured into the annular cavity
to ensure -perfect fitting.

The burners under the combustion tube are then lighted and a moderate
current of air (2-3 bubbles per second) passed through the apparatus, while
the 11 ask is heated carefully so as to bring the liquid to boiling in IO-TJ
minutes. Boiling should be continued lor about ;j hours, the flow of gas
being kept regular and the flame being lowered or removed immediately
if pressure develops in the flask and tends to drive the liquid along the
tube used for the introduction of the acid.

Towards the end the air-current is accelerated a little to displace, all
the carbon dioxide from the apparatus, the absorption apparatus being
afterwards closed, the flames extinguished and the weighings made. The
total carbon in the sample is obtained by multiplying the earbonie anhydride
found by 0-.J727.J.

To ascertain if the sample has been acted on completely, the cold mixture
of sulphuric and chromic- acids is diluted with a huge amount of wafer in
a large beaker and, alter a short lime, the deposit colliding at the bottom
of the beaker is tested for iron particles by means ol a magnet brought, near
to the outside..

The Corleis method is usually adopted lor the analysis of iron, east-iron
and steel, but is unsuitable with products difficult of attack by sulphuric-
chromic, acid mixture, such as ferro silicon, I'erro chromium, I'erro tungsten,
etc. For the latter, the direct combustion method should be used (,sw
later).

Corleis observed that, in the determination of the carbon in steels under
the above, conditions, only .:% of the total carbon iv. liberated as hydro-
carbons, so that the apparatus may be simplified by the suppression of
the combustion tube, the result, then obtained being increased !>'' ,%,

(6) DiKHtrr COMIUISTIUN IN A CUUKI-'.N-I ni- OXVUI-N, This method con-
sists in heating the sample at 1050 '1150" in a current of oxygen and ab-
sorbing the carbon dioxide thus formed in the usual way.

Apfianitits :   (i) Gasometer containing oxygen,

(2)  Wash  bottles  containing'  sodium   hydroxide   solution   ami  cone,
sulphuric add respectively, and a small U tube with calcium chloride.

(3)  A quart/, or externally ghi/,ed porcelain combustion tube (fjo-fk)
cm. long, J'5 cm. bore), closed by rubber stoppers protected I mm the heat
by asbestos board and containing, at the end near the absolution apparatus,
a short layer of euprie oxide to oxidise any carbon monoxide which may
be, formed.

(4)  An electric resistance furnace for  heating  the  tube, with rheostat
and amperemeter (sec I'lg.  n),

(5)  A Le Chatelier thermo-electric couple of platinum anil platinum-IA--5                    5S-Si            2-51